The emergence of Internet Protocol (IP) telephony and IP multimedia networks poses challenges to carriers and service providers, however, it also presents new and expanded business opportunities. The increasing use of IP telephony has spurred development and introduction of numerous telephony services. The use of IP telephony protocols as an interface may assure that a “customer” and a “server” can rely on a common and widely used method for exchanging information. The protocols developed for IP-based services, features, and media transport enable migration of signaling and call-control functionality to intelligent end-user clients. Examples of such protocols include H.323 and the Session Initiation Protocol (SIP). To the extent that telephony services and features can be implemented in intelligent clients, the carriers and service provider network's responsibilities include little more than providing data pipes.
In practice, however, many next-generation services still depend upon network-based servers and support, so network providers are probably in no danger of loosing their ability to sell services. But the trend toward intelligent, IP-based clients is a new dimension in the space of creation and delivery of telephony and media services. At best, carriers, service providers, and device manufacturers may have to work together to ensure interoperability. At worst, carriers and service providers may need to deal with unauthorized delivery of services by intelligent clients in their networks. Either way, maintaining relevance as providers of services, and not just transport of the services, is no longer a given for network providers in a world shared with intelligent clients.
Therefore, if carriers and service providers are to maintain their ability to generate revenue for services offered or supported in their networks, then the service providers' ability to enforce the authorization of service usage is important. This is particularly important in next-generation IP telephony and IP multimedia networks, where many basic and advanced services may be signaled, controlled, and/or delivered by intelligent end-user clients that are not owned or controlled by the network providers, thereby enabling potential bypassing by the end user of service agreements or other subscription accounting mechanisms.